This invention relates to a braking force control apparatus for use with an automotive vehicle.
A wheel cylinder is provided for each of the road wheels on which an automotive vehicle is supported. The braking force applied to the road wheel has been controlled with the use of a solenoid valve(s) operable on electric current having a rectangular waveform to move between its open and closed positions to control the fluid pressure introduced into the wheel cylinder. One problem associated with such electric current is great pulsations which occur particularly when the solenoid valve closes to produce great wheel cylinder pressure fluctuations. The wheel cylinder pressure fluctuations causes vibrations to be transmitted to the vehicle body, as will be described in detail. It is the conventional practice to avoid the disadvantageous wheel cylinder pressure fluctuations by employing an expensive flow control device such as an orifice or damper with the solenoid valve. However, the use of such a flow control device results in a slow braking force control response.